The Sandbox Sitter

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The Sandbox Sitter

Client: Marlese Delgado, UCP Hand in Hand
Students: Josh Parsons, MacNeil Bennett


This work was done by the two high school students, as part of the Jefferson County International Baccalaureate School Work-Study program.  The present project is a modified floor sitter, which allows children with cerebral palsy to sit and play in a sandbox.  It is based on the following dimensions of the user: 10”-15” arm length, 7”-10” shoulder width, 8”-12” seat to shoulder height, with a 50 lbs weight limit. The child is secured in the sitter by a restraining system (seat belts and straps), capable of being loosened and tightened to increase or decrease the pressure/force needed to keep the child’s back and neck in position parallel to the rigid structure.  It does not inhibit lateral, horizontal, or vertical motion of their arms and is lightweight and portable, without compromising the structural integrity of the device.  It is corrosion resistant to water and detergents for cleaning purposes and is lined with a padded material.



The final design was made of wood and aluminum.  The wood was sealed with a non-toxic, dip-coating, which will further prevent warping and bowing associated with environmental conditions such as humidity and temperature. A hinge and lock design mechanism with positive locking pins maintains a backboard structure capable of positions ranging from 20 (folded forward) to 125 (completely extended). The back support is allowed to rotate by a set of wide-leaf utility hinges. They are swaged for mounting into panels and zinc plated to provide maximum protection against rust and corrosion.  Locking pins are used to secure the back supporting structure at the appropriate angle. These pins are positive locking with ball bearings that lock the pin into its receptacle.  The ball, ring, spring, shank, receptacles and spindle are stainless steel.

The sandbox sitter is lined with a urethane padding upholstered in washable vinyl. A four-point chest support strap (Bodypoint harness, Rubatex) along the back supporting structure is used to keep the spine and head erect and aligned. Velcro attaches the chest support to the back support and keeps the child’s pelvis correctly oriented in the chair. Metal end-fittings and slides are provided for a strong, adjustable means of attachment.  Medial placement of secondary straps secures the position of the pad and keeps the hip belt from riding up into the abdomen.  The seat belt is adjustable and locks in place.  An adjustable footrest, purchased form a supply company, is held in place with a set of plastic dowels.  A schematic of the final product, which  cost less than $400, is shown in Figure 7.

7 - sandbox sitter
Figure 7.  The sandbox sitter securely holds and supports a child for seating in a sandbox.  The hinged system provides support at a range of angles, to accommodate numerous children with varying degrees of disability